The present invention relates to a tube cutter having an automatic feed system which will automatically feed a cutting tool into a tube as a cutting head rotates and which will automatically reset the cutting tool to an initial position when the cutting has been completed.
Tools for cutting tubing are well known in the art and typically comprise a rotatable cutting head mounted in a stationary housing. A cutting tool, such as a cutting wheel, is mounted on the cutting head such that it revolves around the tube. Feed means are incorporated in the device to exert a force on the cutting wheel urging it into the tube wall. The cutting tool is revolved about the tube and feed inwardly until it has completely severed the tube wall.
Usually the feed systems of the known devices comprise a cutting tool holder engaged with a threaded feed screw. The feed screw may be rotated by a star wheel attached thereto which contacts a fixed pin during rotation of the cutting head. While these systems serve to adequately feed the cutting tool into the tube wall, retraction of the cutting wheel to its initial position after the tube has been cut requires the feed screw to be turned in the opposite direction, a laborious and time consuming task.
It has also been proposed to provide the cutting device with a helical cam which automatically resets the cutting tool after the cut has been completed. The helical cam is attached to a generally radially extending rod which bears against the cutting tool holder. The rotation of the helical cam produces radial motion of the rod to urge the cutting tool against the tube. The radial movement is caused by the helical surface of the cam bearing against a fixed pin on the cutting head. After a complete revolution of the helical cam, a spring biasing force acting on the cutting tool holder returns the cutting tool to its initial position. The periphery of the helical cam is serrated to form ratchet teeth which contact a separate pawl, also attached to the cutting head, to limit the rotation of the cam to one direction. The serrations also contact a fixed plate, attached to the tube cutter housing so as to advance the cam for each revolution of the cutting head.
The foregoing feed system has been found satisfactory for relatively large tube cutting devices. However, the orientation of the helical cam, the generally radial actuating rod and the separate pawl are impractical in a compact tool cutter designed for cutting tubes having limited access space. Quite obviously, it is necessary to minimize the dimensions of the outer housing of such devices in order to enable the cutter to be placed about the tube. The space requirements of the known automatic feed systems are such that they prevent the use of minimum sized housings, thereby rendering the tube cutters having such feed systems unsuitable for use in limited access areas.